Single-shot spatial coherence characterization of x-ray ultrafast sources

Area of Science:

• Optics and Photonics
• Coherence Theory
• Metrology

Background:

• Spatial coherence is critical for applications like lensless imaging, affecting image formation, especially with source variations.
• Current single-shot spatial coherence measurements often require parallel intensity data or multiple masks, limiting practicality.
• Robust characterization of spatial coherence is essential for advanced optical techniques.

Purpose of the Study:

• To develop a novel single-shot method for measuring spatial coherence length.
• To overcome limitations of existing techniques, such as the need for parallel intensity measurements or multiple masks.
• To create a robust method insensitive to beam-pointing instabilities.

Main Methods:

• Designed a two-dimensional non-redundant array of apertures for spatial coherence measurement.
• Utilized the far-field interference pattern generated by the aperture array.
• Adapted a method based on González et al. [J. Opt. Soc. Am. A28, 1107 (2011)] for single-shot analysis.
• Configured pinholes to decouple spatial coherence from intensity distribution.

Main Results:

• Achieved single-shot measurement of spatial coherence length.
• Demonstrated robustness against beam-pointing instabilities.
• Successfully disentangled spatial coherence from intensity distribution, eliminating the need for parallel intensity measurements.
• Experimentally validated the method using a high-harmonic source.

Conclusions:

• The proposed aperture array method enables efficient and robust single-shot spatial coherence characterization.
• This technique simplifies measurements in fields like lensless imaging and metrology.
• The method's insensitivity to source variations enhances its applicability in dynamic optical systems.